Belowground Edible Plants

Dive into the world of botany with this quick guide on underground, edible plants.

August 2018
By Katie Scott and Kathy Willis

Cover courtesy of Templar Company Limited

Botanicum (Big Picture Press, 2017) by Katie Scott and Kathy Willis is a scientific and artistic introduction to the world of botany. With vivid illustrations by Scott and descriptive text by Willis, a professor of Biodiversity at the University of Oxford and director of science at the Royal Botanic Gardens, the botanical guide is both educational and enjoyable. Scott is also the illustrator to a sister book,Animalium. The following excerpt discusses the hardy and edible plants that grow underground.

Some plants stay alive during cold and dry seasons by storing starches, proteins, and other nutrients underground in roots, rhizomes, or tubers. Many food crops are provided by these belowground storage organs, including the world’s fourth most important food source, the potato, which is a tuber.

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Root vegetables include carrots, turnips, rutabagas, parsnips, mangel-wurzel, black salsify, and radishes. Below ground, they grow as a swollen root in a variety of shapes. Leaves grow directly from the aboveground shoulder of this tap root, and there is little or no aboveground stem, only leaves.

By contrast with root vegetables, rhizomes and tubers grow from leafy plants with aboveground stems. Potato plants are leafy, branched green plants with small white flowers. Plants that grow rhizomes and tubers also grow the normal kind of root. Rhizomes often form unusual shapes, such as the knobby underground part of ginger, and are actually roots merged together, usually growing vertically downward in the soil.The word rhizome derives from the ancient Greek for “mass of roots.”

Tubers include potatoes, sweet potatoes, oca, and yams. A tuber is a short, thick, round stem or root that grows underground, usually as an offshoot from the main stem of the plant.Tubers contain all the necessary parts to produce a new plant. If you leave a potato in a kitchen drawer for too long, for example, it will sprout.

One other belowground food deserves a mention: peanuts. Peanuts are not actually nuts but the seeds of a legume, a plant in the pea family. Peanut flowers grow in clusters on the stems, just above ground. After they are fertilized, a short stalk at the base of the ovary forms, pushing the seed into the soil, where it develops into a mature peanut pod.

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Illustration by Katie Scott

Key to Plate

1: Potato

Solanum tuberosum

Plant height: up to 3 feet/1 meter

2: Winged yam

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Dioscorea alata

Tuber diameter: around 2-1/2 inches/6 centimeters

Tuber cut horizontally

Winged yams were domesticated in Southeast Asia and the Pacific but are now eaten in many tropical countries.

3: Beet

Beta vulgaris

Plant height: up to 61/2 feet/2 meters in flower

Root diameter: around 4 inches/10 centimeters

Root cut horizontally

4: Oca

Oxalis tuberosa

Tuber length: up to 3 inches/8 centimeters

Tuber

Oca is a crop plant that originated in the Andes, in South America.

5: Radish

Raphanus sativus

Root length: 3/4 inch–3 feet/2 centimeters–1 meter

The radish is an edible root vegetable that was domesticated in Europe in pre-Roman times.

6: Carrot

Daucus carota

Root length: 51/2–10 inches/14–25 centimeters

7: Black Salsify

Scorzonera hispanica

Root length: 8 inches–3 feet/20 centimeters–1 meter

8: Turnip

Brassica rapa

Root diameter: 2–8 inches/5–20 centimeters

Root

9: Peanut

Arachis hypogaea

Stem height: up to 28 inches/ 70 centimeters

Pod length: 1-1/8 –2-3/4 inches/3–7 centimeters

10: Ginger

Zingiber officinale

Shoot height: up to 4 feet/1.2 meters The rhizome of ginger comes from Asia.

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